An Efficient Synthesis of N-(Hetero)arylcarbazoles: Palladium-Catalyzed Coupling Reaction between (Hetero)aryl Chlorides and N-Carbazolylmagnesium Chloride

An efficient method for the synthesis of N‐(hetero)arylcarbazoles, useful compounds for functional materials, is reported. Various (hetero)aryl chlorides reacted with N‐carbazolylmagnesium chloride in the presence of a palladium catalyst (0.05 to 0.2 mol%) prepared from allylpalladium(II) chloride dimer {[PdCl(allyl)]2} and di‐tert‐butyl(2,2‐diphenyl‐1‐methylcyclopropan‐1‐yl)phosphine (cBRIDP) under mild conditions (110 °C) in a short period of time (15 min to 2 h) to give N‐(hetero)arylcarbazoles in high yields. The reactions of bromochlorobenzenes proceeded in favour of the bromo group to afford N‐(chlorophenyl)carbazoles in a highly selective manner. Functional materials for use in organic light‐emitting diodes, such as mCP, 26mcPy, CBP and TCB, were also obtained in high yields within 15 min by the reaction of (hetero)aryl polyhalides. Optimization of the reaction conditions and a postulated catalytic cycle for the reaction are also discussed.